Specifications

Section 6 The Selected Alternative Plan
EAA Storage Reservoirs Revised Draft PIR and EIS February 2006
6-34
For the Caloosahatchee Estuary, the NAI alternative plans are slightly better
than the future without project. During the dry season, the NAI alternative
plans show increased number of months with flows less than 300 cfs with no
substantial differences between the alternatives. This increase would negatively
affect the salinity conditions within the estuary. For the St. Lucie Estuary, the
NAI alternative plans are slightly better than the future without project. The 14-
day moving-average of flows greater than 2000 cfs, including lake releases, is
better for the NAI alternative plans than the future without project. For Lake
Worth Lagoon there were no significant differences between the future without
project and the NAI alternative plans.
Larger Lake Okeechobee regulatory releases to the south benefit the system by
reducing adverse impacts to estuaries and lowering seasonally high stages in the
lake. Fewer water supply releases from Lake Okeechobee for EAA irrigation are
considered a benefit, leaving more water in the lake for the natural system.
Water supply to the EAA from Lake Okeechobee under the NAI is less than half
that of the future without project condition. Significant increases in
evapotranspiration result in a reduction in total water available in the regional
system. However, total losses from evapotranspiration under the next added
increment are much lower than the total losses to tide under the future without
project condition and direct rainfall into the reservoir also offsets
evapotranspiration losses.
In the Greater Everglades, there are no significant differences between the four
NAI alternative plans, or between the NAI alternative plans and the future
without project condition when the full 36-year POR is averaged; however,
RECOVER did note some small differences, suggesting that significant
differences might be observed if only the wettest and driest years were
examined. There were consistent small differences between the four NAI
alternative plans and the future without project condition in the marl marsh
indicator regions. Similarly, there was a small difference between the four NAI
alternative plans and the future without project for GE-E1, suggesting that the
project may provide some benefit in terms of fewer dryouts in Shark River
Slough.
The EAA storage reservoir provides water quality treatment benefits both
within reservoir as well as down stream in the STAs. The reservoir itself
provides additional retention time increases, the settling rate of particulate
matter lowering water column TP along the flow path of the STA, and
maintaining TP loads further away from the GE. Additional storage capacity in
the reservoir will aid in keeping STAs saturated during the dry season,
potentially lowering the level of nutrient flux from sediments. Lowering the
volume delivered to the STAs lowers the probability that STAs will be loaded